CN114435181A

CN114435181A - System and method for managing battery of vehicle

Info

Publication number: CN114435181A
Application number: CN202111140084.5A
Authority: CN
Inventors: 李成一; 姜旻秀; 白起昇
Original assignee: Hyundai Motor Co; Kia Corp
Current assignee: Hyundai Motor Co; Kia Corp
Priority date: 2020-11-03
Filing date: 2021-09-28
Publication date: 2022-05-06
Also published as: KR20220060083A

Abstract

The invention relates to a system and a method for managing a battery of a vehicle. A battery management system of a vehicle includes a first controller configured to control an ON (IG ON) state and an OFF (IG OFF) state of a plurality of controllers, and a second controller including a Real Time Clock (RTC) and configured to be awakened by directly receiving power from a secondary battery at a preset time period calculated based ON a count value provided from the RTC at intervals within a preset reference period when the OFF state is turned ON by the first controller, and to monitor states of the primary battery and the secondary battery.

Description

System and method for managing battery of vehicle

Technical Field

The present invention relates to a system and method for managing a battery of a vehicle, and more particularly, to a system and method for managing a battery of a vehicle, which prevents various problems occurring in a power-off state of the battery in advance by effectively monitoring the state of the battery through various controllers in the vehicle in the power-off state after the vehicle stops running.

Background

Generally, an eco-friendly vehicle driven using electric energy generates power by driving a motor, which is an electric rotating device, using electric energy stored in a battery. The dynamic performance of environmentally friendly vehicles is closely related to the performance of batteries, and thus effective monitoring and management of batteries is essential.

Generally, a Battery of an eco-friendly vehicle is managed by a controller, which is collectively called a Battery Management System (BMS). The BMS collects various pieces of information (battery voltage, battery current, or battery temperature) for management of the battery from the battery, and calculates various parameters for management of the battery by applying the collected information to various pre-stored algorithms.

A conventional vehicle battery management scheme is mainly performed in a state in which power is supplied to a controller called a Battery Management System (BMS), i.e., an energized (IG ON) state or a state in which power is supplied to a controller associated with a battery (IG3 ON).

In a conventional vehicle battery management scheme, a main relay connected to a battery monitors the battery through IG ON in a state where an electrical connection is made between the battery and other components (e.g., a power module for converting electric power of the battery and supplying the converted electric power to a motor or a charger to generate electric power to charge the battery), or in a state where electric power is supplied to various controllers related to the battery through IG3 ON.

Accordingly, in the conventional vehicle battery management scheme, since information for management of the battery is collected in a state where electrical connection between the battery and other components is achieved, there is a problem in that the state of the battery is not accurately monitored due to the influence of the other components on the collected information, or power is supplied to other controllers that do not need to be operated during monitoring of the battery, thereby causing unnecessary power loss.

The contents of the description of the related art are provided only to aid in understanding the background of the present invention and should not be construed as being equivalent to the prior art known to those having ordinary skill in the art.

Disclosure of Invention

An object of the present invention is to provide a system and method for managing a battery of a vehicle for preventing an accident such as battery burn in advance by effectively monitoring the battery without wasting power in a state where the vehicle is powered off.

According to an embodiment of the present invention, a battery management system of a vehicle, which includes a main battery for storing driving power of the vehicle and a sub-battery having a lower voltage output than the main battery and storing power for a plurality of controllers in the vehicle, includes a first controller configured to control an ON-state (IG ON) and an OFF-state (IG OFF) of the plurality of controllers, and a second controller including a Real Time Clock (RTC) and configured to be awakened by directly receiving power from the sub-battery at intervals of a preset Time calculated based ON a count value provided from the RTC within a preset reference period when the OFF-state is turned ON by the first controller, and configured to monitor states of the main battery and the sub-battery.

The second controller may be configured not to monitor the states of the main battery and the sub-battery after a preset reference time period elapses.

The second controller may be configured to operate in a power blocking mode, which is performed by directly receiving power from the sub-battery during a preset reference period when the power-off state is started by the first controller, and to be woken up at a preset time interval period after the power blocking mode is terminated.

The second controller may be configured to turn off a main relay for connecting/interrupting an output of the main battery and check a condition that the states of the main battery and the sub-battery are not monitored, when the power-off state is started by the first controller.

As a condition, when a State of Charge (SoC) of a sub-battery for supplying voltages of the first controller and the second controller cannot be checked, when the SoC of the main battery is lower than a preset reference value, when communication with the first controller or a low voltage DC-DC converter for reducing the voltage of the main battery and applying the reduced voltage to the sub-battery is impossible, or when the low voltage DC-DC converter malfunctions, the second controller may be configured not to monitor states of the main battery and the sub-battery.

The second controller may be configured to check whether a main relay connected to the main battery is short-circuited after waking up, and start a preset time calculated in advance based on a count value provided by the RTC when a state of the main relay short-circuited is changed to a power-off state.

When the SoC of the sub-battery is less than or equal to a preset reference value as a monitoring result of the states of the main battery and the sub-battery, the second controller may be configured to turn on a main relay connected to the main battery after waking up and may operate a low voltage DC-DC converter for lowering the voltage of the main battery and applying the lowered voltage to the sub-battery to charge the sub-battery by lowering the voltage of the main battery and applying the lowered voltage to the sub-battery.

When the charging of the secondary battery is terminated, the second controller may be configured to turn off the main relay and continue to hold the preset time calculated in advance based on the count value provided by the RTC, instead of resetting the preset time.

The preset reference time period may be determined based on an analysis result of a Vehicle Customer Relationship Management (VCRM) system for collecting and analyzing Vehicle travel information, or a preset limit of a state of charge (SoC) of the sub-battery consumed by a dark current after the Vehicle stops traveling.

According to another embodiment of the present invention, a battery management method of a vehicle includes: when an external input to stop the vehicle from running is generated, a plurality of controllers in the vehicle are controlled to be in a power-off state by a first controller, a power blocking mode is performed by a second controller, and a main relay connected to a main battery for storing driving power of the vehicle is turned off, the power blocking mode is terminated, the power blocking mode is awakened by directly receiving power from a sub-battery at intervals within a preset reference period of time based on a period of a preset time calculated from a count value provided from a Real Time Clock (RTC) installed in the second controller, and states of the main battery and the sub-battery are monitored by the second controller.

The method may further comprise: after the main relay is turned off, a condition that the states of the main battery and the sub-battery are not monitored is checked, and when the condition is satisfied, the states of the main battery and the sub-battery are not monitored.

Not monitoring the state of the main battery and the sub-battery may include: as a condition, when a State of Charge (SoC) of a sub-battery for supplying voltages of a first controller and a second controller cannot be checked, when the SoC of a main battery is lower than a preset reference value, when communication with the first controller or a low voltage DC-DC converter for reducing the voltage of the main battery and applying the reduced voltage to the sub-battery is impossible, or when the low voltage DC-DC converter malfunctions, the second controller does not monitor states of the main battery and the sub-battery.

Monitoring the states of the main battery and the sub-battery may include: the second controller checks whether a main relay connected to the main battery is short-circuited after waking up, and starts a preset time pre-calculated based on a count value provided by the RTC by the second controller when a state of the main relay short-circuited is changed to a power-off state.

Monitoring the states of the main battery and the sub-battery may include: when SoC of the sub-battery is less than or equal to a preset reference value as a monitoring result of states of the main battery and the sub-battery, the second controller turns on a main relay connected to the main battery after waking up, and operates a low voltage DC-DC converter for lowering a voltage of the main battery and applying the lowered voltage to the sub-battery to charge the sub-battery by lowering the voltage of the main battery and applying the lowered voltage to the sub-battery.

Monitoring the states of the main battery and the sub-battery may include: when the charging of the secondary battery is terminated, the main relay is turned off and the preset time calculated in advance based on the count value provided by the RTC is continuously maintained, instead of resetting the preset time.

Drawings

Fig. 1 is a block diagram showing the configuration of a vehicle battery management system according to an embodiment of the invention.

Fig. 2 is a schematic diagram showing a monitoring process of a vehicle battery management system over time according to an embodiment of the present invention.

Fig. 3 and 4 are flowcharts illustrating a vehicle battery management method according to an embodiment of the present invention.

Detailed Description

Hereinafter, a system and method of managing a battery of a vehicle according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to fig. 1, a vehicle battery management system according to an embodiment of the present invention may include a main battery 13 for storing driving power of a vehicle, and a sub-battery 15 having a lower voltage output than the main battery 13 and storing a plurality of controller powers for use in the vehicle. The vehicle battery management system according to the embodiment of the invention may further include a first controller 11 and a second controller 12, the first controller 11 for controlling an ON (IG ON) state and an OFF (IG OFF) state of the plurality of controllers, the second controller 12 having a Real Time Clock (RTC)121, the second controller 12 waking up the second controller 12 by directly receiving power from the sub-battery 15 at intervals of a preset Time based ON a count value provided from the RTC 121 when the OFF state is turned ON by the first controller 11, and the second controller 12 monitoring states of the main battery 13 and the sub-battery 15.

As shown in fig. 1, the first controller 11 may be embodied as a Vehicle Control Unit (VCU) for controlling the overall operation of the Vehicle, and the second controller 12 may be embodied as a controller called a Battery Management System (BMS) that mainly monitors the state of the Battery and controls the state of a Main Relay (MR) connected to the Battery, and the like, but the present invention is not limited thereto. For example, the second controller 12 may be embodied as a Hybrid Control Unit (HCU), a Low voltage DC-DC Converter (LDC) controller, or the like, and the second controller 12 is other controller included in the vehicle, including a motor driven using energy stored in a battery.

The main battery 13 may be a main battery (or a high voltage battery) of the vehicle, which is charged by supplying energy to the driving motor for generating power of the vehicle or receiving energy regeneration of the driving motor.

The sub-battery 15 may be a battery for supplying voltage to various controllers including the first controller and the second controller and electric loads in the vehicle, and may be a battery having a lower voltage output than the main battery 13.

A low voltage DC-DC converter (LDC) for reducing the high voltage of the main battery 13 to the voltage of the sub-battery 15 or a voltage corresponding to the electric power of a controller or an electric load in the vehicle may be provided between the main battery 13 and the sub-battery 15. The second controller 12 may control the low voltage DC-DC converter 14, and may charge the sub-battery 15 by reducing the voltage of the main battery 13 and supplying the reduced voltage to the sub-battery 15.

According to an embodiment of the present invention, the first controller 11 may control an ON (IG ON) state or an OFF (IG OFF) state of a plurality of controllers in the vehicle based ON a signal (e.g., a start button) input from the outside. For example, in the power-off state, when the driver generates an input of pressing a start button of the vehicle, the first controller 11 may recognize the input and may supply power to a plurality of other controllers in the vehicle to change the current state to a power-ON (IG ON) state. On the other hand, in the power-on state, when the driver generates an input of pressing the start button of the vehicle, the first controller 11 may recognize the input and may interrupt the supply of electric power to a plurality of other controllers in the vehicle to change the current state to the power-OFF (IG OFF) state.

The second controller 12 may be operated according to the power-on or power-off state control performed by the first controller 11, and according to the input of the driver, after the power-on state is changed to the power-off state immediately when the vehicle stops running, the second controller 12 may turn off the Main Relay (MR) using a power latch function installed therein while maintaining the power-on state for a predetermined time. Here, the Main Relay (MR) may be a relay for connecting or interrupting the output of the main battery 13 to the vehicle system or the output from the vehicle system to the main battery 13, and when the Main Relay (MR) is turned off and becomes an open state, all systems in the vehicle may become in a state in which it is not possible to receive electric power from the Main Relay (MR).

The power blocking function or the power blocking mode may be a function of maintaining a state of supplying power for a predetermined time using a power line directly connected to the sub-battery 15, the sub-battery 15 supplying power through the second controller 12 as needed even IF the first controller 11 performs power OFF (IF OFF) control. That is, the second controller 12 may make an electrical connection with the sub-battery 15 to directly receive power therefrom, regardless of the power line (e.g., IG line) controlled by the first controller 11. In general, the electric power directly connected to the sub-battery 15 may also be referred to as continuous electric power. According to an embodiment of the present invention, the first controller 11 and the second controller 12 may be connected to continuous power and may be continuously operated with a wake-up function that performs a predetermined time in each cycle to prevent the sub-battery 15 from being discharged using the continuous power.

The second controller 12 may mainly measure an insulation resistance value of the main battery 13 and may monitor a voltage deviation between battery cells included in the main battery 13, a degree of deterioration of the main battery 13, a voltage of the sub-battery 15, and the like to check problems occurring in the main battery 13 and the sub-battery 15 after the vehicle stops running and is powered off.

The insulation resistance of the battery, the voltage deviation between the battery cells, and the degree of deterioration may be obtained or calculated using various schemes known in the art, and detailed schemes for obtaining or calculating the insulation resistance of the battery, the voltage deviation between the battery cells, and the degree of deterioration are not directly related to the spirit of the present invention, and detailed descriptions thereof are accordingly omitted.

According to the control of the first controller 11, after the power-OFF (IG OFF) state of the vehicle is turned on, the second controller 12 may automatically wake up at intervals of a preset time period using a Real Time Clock (RTC)121 installed therein and may monitor the main battery 13 and the sub-battery 15.

When a driver input (a start button input in an energized state) to stop the vehicle from running is generated, the first controller 11 may turn on an OFF (IG OFF) state in which a plurality of controllers in the vehicle are de-energized. As such, when the power-ON (IG ON) state is converted to the power-OFF (IG OFF) state, the power-OFF (IG OFF) state may be turned ON while the second controller 12 may perform the power lock-up mode. The reference time for maintaining the power blocking mode may be preset to about several hours.

When the power lock-up mode is terminated, the second controller 12 may be powered off, the second controller 12 may be woken up at intervals of each preset time period within a preset reference period, and the second controller 12 may monitor the main battery 13 and the sub-battery 15 for preset times.

For example, the reference time for monitoring the battery through the power-off and wake-up operations of the second controller 12 may be about several days. According to the analysis of a Vehicle Customer Relationship Management (VCRM) system for collecting and analyzing various pieces of information on the traveling of a Vehicle, most drivers will turn on the Vehicle again within at least 7 days after the Vehicle stops traveling. Further, the state of charge (SoC) of the sub-battery 15 consumed by the dark current after the vehicle stops running may be limited by each vehicle manufacturer. The reference time for monitoring the battery through the power-off and wake-up operations of the second controller 12 may be appropriately determined according to the analysis result of the VCRM system or the specification for managing the dark current applied to the sub-battery of the vehicle.

The second controller 12 may accumulate the number of times the second controller 12 is woken up per period of time, may check a reference time for monitoring the battery, and may stop monitoring when the reference time elapses.

The time interval at which the second controller 12 wakes up may be appropriately determined according to the lifetime of the memory 122 included in the second controller 12. For example, the number of writes that can be performed to the EEPROM serving as a memory can be secured to a certain number or less. In view of the guaranteed number of writes of the EEPROM and the maximum number of times the EEPROM performs writes during the wake-up of the second controller 12, the wake-up time interval may be determined in such a manner that the maximum number of writes of the EEPROM during the expected life of the vehicle is not greater than the guaranteed number of writes.

In addition, the time for monitoring the main battery 13 and the sub-battery 15 after the second controller 12 wakes up may be appropriately determined with reference to the number of times the monitoring item (e.g., measurement of the insulation resistance) is performed for each battery or the time for performing the monitoring item.

According to various embodiments of the present invention, the main battery 13 may be monitored in a state where the vehicle is powered OFF (IG OFF) and the main battery 13 is not connected to the vehicle system, that is, in a state where the Main Relay (MR) is turned OFF (short-circuited). Therefore, the above monitoring can be performed when the state in which the main battery 13 is not connected to the vehicle system is maintained. During the above-described monitoring process, when the electrical connection state of the main battery 13 is changed, that is, when the Main Relay (MR) is turned on (closed), the battery monitoring according to various embodiments of the present invention may be stopped and the monitoring process may be started, and when the Main Relay (MR) is turned off again, the battery monitoring may be restarted from the initial procedure for the battery monitoring, that is, the power blocking mode of the second controller 12 is performed.

According to various embodiments of the present invention, when the SoC of the sub-battery 15 is lower than the preset reference value, the second controller 12 may charge the sub-battery 15 by turning on the Main Relay (MR), driving the low-voltage DC-DC converter 14, reducing the voltage of the main battery 13, and supplying the reduced voltage to the sub-battery 15. In this case, even if the Main Relay (MR) is turned on, the monitoring process may not be started. This is because, if the SoC of the sub-battery 15 is low and the main relay is turned on to start the monitoring process, the charging of the sub-battery 15 and the new monitoring process are continuously repeated and cannot be terminated within a preset time.

When the driver presses the vehicle start button to generate an input for turning OFF the vehicle after the vehicle stops running and the first controller 11 controls the controller of the vehicle to be in an OFF (IG OFF) state, the second controller 12 may turn OFF the Main Relay (MR) while maintaining power using the power blocking function, and then may determine whether the requirement of monitoring the main battery 13 is satisfied.

Here, as a requirement for monitoring the main battery 13, it may be considered whether to calculate a state of charge (SoC) of the sub-battery 15, SoC of the main battery 13, a communication state between controllers, and the like.

For example, when the second controller 12 cannot check the SoC of the sub-battery 15 that supplies electric power to the

controllers

11 and 12, the first controller 11 and the second controller 12 may not be able to check whether or not sufficient electric power can be supplied for monitoring the main battery 13 in a state where the sub-battery 15 is not charged, and thus monitoring of the main battery 13 may not be performed.

The low-voltage DC-DC converter 14 may operate to charge the sub-battery 15 with energy stored in the main battery 13 and perform battery monitoring when the SoC of the sub-battery 15 is lower than a preset reference value, and may lower the SoC of the main battery 13 and may fail to drive the vehicle if the sub-battery 15 is charged when the SoC of the main battery 13 is insufficient. Therefore, when the SoC of the main battery 13 is lower than the preset reference value, monitoring may not be performed.

When communication between the first controller 11 and the second controller 12 or communication (for example, CAN communication) between the second controller 12 and the low-voltage DC-DC converter 14 is not possible (for example, CAN timeout), various data necessary for performing monitoring cannot be exchanged, and thus monitoring cannot be performed.

When the low-voltage DC-DC converter 14 is determined to be faulty (for example, an error code of the low-voltage DC-DC converter 14 is generated), the sub-battery 15 cannot be charged, and therefore monitoring cannot be performed.

Fig. 3 and 4 are flowcharts illustrating a vehicle battery management method according to an embodiment of the present invention. The vehicle battery management method according to the embodiment of the invention may be performed by the above-described vehicle battery management system according to the embodiment of the invention.

Referring to fig. 3 and 4, when the driver generates an input to stop the running of the vehicle in a state where the vehicle is parked, the method may be performed from step S11 in which the controller in the vehicle is powered off by the first controller 11.

When the controller enters an OFF state (IG OFF) through the first controller 11, the second controller 12 may turn OFF the Main Relay (MR) while maintaining power with the power blocking function (S12), and may check whether the requirement for performing monitoring is satisfied (S13) in a state where the Main Relay (MR) is turned OFF.

At step S13, the second controller 12 may determine that monitoring is not to be performed if: it is not possible to check the SoC of the sub-battery 15 for supplying the voltages of the first controller 11 and the second controller 12, the SoC of the main battery 13 being lower than a preset reference value, the low-voltage DC-DC converter 14 for reducing the voltage of the main battery 13 and applying the reduced voltage to the sub-battery 15 failing, or to communicate with the low-voltage DC-DC converter 14 or the first controller 11.

When the requirement to perform the monitoring at step S13 is satisfied, the power blocking mode may be terminated (S14), and the second controller 12 may run the RTC 121 installed therein, and then the second controller 12 may be turned off (S15).

Then, the second controller 12 may be woken up with continuous power based on the count value of the RTC 121 (S21). The wake-up performed at step S21 may wake up only the second controller 12 based on the count value of the RTC installed in the second controller 12, and may not wake up the first controller 11. Accordingly, it is possible to interrupt the supply of electric power to other controllers or electric loads by waking up the first controller 11, thereby reducing the consumption of electric power generated after the vehicle stops running.

Then, the awakened second controller 12 may determine whether to awaken the second controller 12 according to the input of the driver or to wake up the second controller 12 by energizing the vehicle through the awakened first controller 11 (S22).

When the second controller 12 is woken up to perform the battery monitoring based on the count of the RTC 121 installed therein, the second controller 12 may monitor the main battery 13 and the sub-battery 15 for a preset time (S23).

As a result of the monitoring, when the SoC of the sub-battery 15 is less than or equal to the preset reference value (S24), the second controller 12 may turn on the Main Relay (MR) and may operate the low voltage DC-DC converter 14 to charge the sub-battery 15 to have a SoC value greater than the preset reference value.

When the SoC of the sub-battery 15 is greater than the reference value at step S24 or after the sub-battery 15 is charged at step S25, the second controller 12 may check whether a preset reference time for performing monitoring has elapsed (S26), and when the reference time has not elapsed, the controller 12 may power off until the next monitoring is performed, and when the reference time has elapsed, the controller 12 may terminate the monitoring process.

When the second controller 12 wakes up and is powered ON (S21) and it is determined from the input of the driver that the reason for becoming the energized state is the energized (IG ON) state under the control of the first controller 11 (S22), the second controller 12 may determine whether the Main Relay (MR) needs to be turned ON (S27), and when the Main Relay (MR) is turned ON, may start a counter (S28). That is, the state of the battery may be changed when the first controller 11 is connected to the vehicle system by turning on the Main Relay (MR), and the monitoring of the battery, which is previously performed, may be terminated.

After the counter is started (S28), when the vehicle becomes the power-OFF (IG OFF) state again by the first controller 11, the method may proceed to step S13 to perform the above-described monitoring process again from the beginning. After the counter is started (S28), the vehicle may start running, instead of being changed to the power-OFF (IG OFF) state again by the first controller 11, the monitoring process may be terminated.

As described above, in the system and method of managing a battery of a vehicle according to various embodiments of the present invention, in a state where the vehicle stops running, the state of the battery can be monitored by periodically waking up only a controller for managing a battery system of the vehicle based on an RTC installed in the controller, and thus it is possible to prevent other controllers unrelated to the battery system from being woken up when monitoring the battery, thereby reducing power consumption due to battery monitoring in the state where the vehicle stops running.

In particular, in the system and method for managing a vehicle battery according to various embodiments of the present invention, the number of times battery monitoring is performed may be appropriately determined as time passes after a power-off state starts, and thus the state of the battery may be effectively monitored while minimizing power consumption in the power-off state.

In the system and method for managing a vehicle battery, in a state where a vehicle stops running, a battery state can be monitored by periodically waking up only a controller for managing a vehicle battery system, in which an RTC is installed, based on the RTC, and thus it is possible to prevent other controllers unrelated to the battery system from being woken up when monitoring the battery, thereby reducing power consumption due to battery monitoring in the state where the vehicle stops running.

In particular, in a system and method of managing a vehicle battery, the number of times battery monitoring is performed may be appropriately determined as time passes after a power-off state starts, and thus the state of the battery may be effectively monitored while minimizing power consumption in the power-off state.

The first controller 11 may comprise a processor or microprocessor. In addition, the first controller 11 may further include a memory. The above-described operations/functions of the first controller 11 may be embodied as computer readable codes/algorithms/software stored on a memory thereof, which may include a non-volatile computer readable recording medium. The non-volatile computer-readable recording medium is any data storage device that can store data which can be thereafter read by a processor or microprocessor. Examples of the computer-readable recording medium include: hard Disk Drives (HDDs), Solid State Drives (SSDs), Silicon Disk Drives (SDDs), Read Only Memories (ROMs), Random Access Memories (RAMs), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and the like. The processor or microprocessor may perform the above-described operations/functions of the first controller 11 by executing computer-readable codes/algorithms/software stored on a non-volatile computer-readable recording medium.

Similarly, the second controller 12 may include a processor or microprocessor. In addition, the second controller 12 may also include a memory. The above-described operations/functions of the second controller 12 may be embodied as computer readable codes/algorithms/software stored on a memory thereof, which may include a non-volatile computer readable recording medium. The processor or microprocessor may perform the above-described operations/functions of the second controller 12 by executing computer-readable codes/algorithms/software stored on the non-volatile computer-readable recording medium.

It will be understood by those skilled in the art that the effects achievable by the present invention are not limited to those that have been specifically described above, and other effects of the present invention that are not mentioned will be more clearly understood from the above detailed description.

While the invention has been shown and described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. A battery management system of a vehicle including a main battery for storing driving electric power of the vehicle and a sub-battery having a lower voltage output than the main battery and storing electric power for a plurality of controllers in the vehicle, the battery management system comprising:

a first controller configured to control power-on and power-off states of the plurality of controllers; and

a second controller including a real-time clock, the second controller being configured to be awakened by directly receiving power from the sub-battery at a preset time period calculated at intervals within a preset reference period based on a count value provided from the real-time clock when the power-off state is turned on by the first controller, and the second controller being configured to monitor states of the main battery and the sub-battery.

2. The battery management system of the vehicle according to claim 1, wherein the second controller is configured not to monitor the states of the main battery and the sub-battery after a preset reference time period elapses.

3. The battery management system of the vehicle according to claim 1, wherein the second controller is configured to: operating in a power blocking mode, which is performed by directly receiving power from the sub-battery during a preset reference period when the power-off state is turned on by the first controller, and waking up at a period of a preset time interval after the power blocking mode is terminated.

4. The battery management system of the vehicle according to claim 1, wherein the second controller is configured to: when the power-off state is turned on by the first controller, a main relay for connecting/interrupting the output of the main battery is turned off, and a condition that the states of the main battery and the sub-battery are not monitored is checked.

5. The battery management system of a vehicle according to claim 4, wherein as the condition, when a state of charge of a sub-battery for supplying voltages of the first controller and the second controller cannot be checked, when the state of charge of the main battery is lower than a preset reference value, when communication with the first controller or the low voltage DC-DC converter for reducing the voltage of the main battery and applying the reduced voltage to the sub-battery is impossible, or when the low voltage DC-DC converter malfunctions, the second controller is configured not to monitor states of the main battery and the sub-battery.

6. The battery management system of the vehicle according to claim 1, wherein the second controller is configured to check whether a main relay connected to the main battery is short-circuited after waking up, and to start a preset time calculated in advance based on a count value provided by the real-time clock when a state of the main relay short-circuited is changed to a power-off state.

7. The battery management system of a vehicle according to claim 1, wherein when the state of charge of the sub-battery is less than or equal to a preset reference value as a result of monitoring the states of the main battery and the sub-battery, the second controller is configured to turn on a main relay connected to the main battery after waking up and operate a low voltage DC-DC converter for stepping down the voltage of the main battery and applying the stepped-down voltage to the sub-battery to charge the sub-battery by stepping down the voltage of the main battery and applying the stepped-down voltage to the sub-battery.

8. The battery management system of the vehicle according to claim 7, wherein when the charging of the sub-battery is terminated, the second controller is configured to turn off the main relay and continue to hold the preset time calculated in advance based on the count value provided by the real-time clock, instead of resetting the preset time.

9. The battery management system of a vehicle according to claim 1, wherein the preset reference time period is determined based on an analysis result of a vehicle customer relationship management system for collecting and analyzing vehicle travel information, or a preset limit of a state of charge of the sub-battery consumed by dark current after the vehicle stops traveling.

10. A battery management method of a vehicle, the method comprising:

controlling, by a first controller, a plurality of controllers in a vehicle to be in a power-off state when an external input that stops traveling of the vehicle is generated;

performing, by the second controller, a power locking mode and turning off a main relay connected to a main battery for storing driving power of the vehicle;

the power locking mode is terminated, awakened by directly receiving power from the sub-battery at a preset reference period of time at intervals based on a period of a preset time calculated from a count value provided from a real-time clock installed in the second controller, and the states of the main battery and the sub-battery are monitored by the second controller.

11. The battery management method of a vehicle according to claim 10, further comprising:

after the main relay is turned off, a condition that the states of the main battery and the sub-battery are not monitored is checked, and when the condition is satisfied, the states of the main battery and the sub-battery are not monitored.

12. The battery management method of a vehicle according to claim 11, wherein not monitoring the states of the main battery and the sub-battery includes: as the condition, the second controller does not monitor the states of the main battery and the sub-battery when the state of charge of the sub-battery for supplying the voltages of the first controller and the second controller cannot be checked, when the state of charge of the main battery is lower than a preset reference value, when communication with the first controller or the low voltage DC-DC converter for reducing the voltage of the main battery and applying the reduced voltage to the sub-battery is impossible, or when the low voltage DC-DC converter malfunctions.

13. The battery management method of a vehicle according to claim 10, wherein monitoring the states of the main battery and the sub-battery includes:

the second controller checks whether a main relay connected with the main battery is short-circuited after being awakened;

when the state of the main relay short circuit is changed to the power-off state, a preset time calculated in advance based on the count value provided by the real-time clock is started by the second controller.

14. The battery management method of a vehicle according to claim 10, wherein monitoring the states of the main battery and the sub-battery includes:

when the state of charge of the sub-battery is less than or equal to a preset reference value as a monitoring result of the states of the main battery and the sub-battery, the second controller turns on a main relay connected to the main battery after waking up and operates a low voltage DC-DC converter for lowering the voltage of the main battery and applying the lowered voltage to the sub-battery to charge the sub-battery by lowering the voltage of the main battery and applying the lowered voltage to the sub-battery.

15. The battery management method of a vehicle according to claim 14, wherein monitoring the states of the main battery and the sub-battery includes: when the charging of the sub-battery is terminated, the main relay is turned off and the preset time calculated in advance based on the count value provided by the real-time clock is continuously maintained, instead of resetting the preset time.